A light emitting device, for example, a light emitting diode (LED), which is a kind of a semiconductor device to convert electrical energy into light, has been spotlighted as a next-generation light source in substitution for a conventional fluorescent lamp and a glow lamp.
Since the LED generates the light by using the semiconductor device, the LED may represent significantly low power consumption as compared with the glow lamp that generates the light by heating tungsten or the fluorescent lamp that generates the light by urging ultraviolet ray, which is generated through the high-voltage discharge, to collide with a fluorescent substance.
In addition, since the LED generates the light by using the potential gap of the semiconductor device, the LED represents a longer life span, a rapider response characteristic, and a more eco-friendly feature as compared with those of a convention light source.
In this regard, various studies have been performed to substitute the conventional light source with the LEDs. The LEDs are increasingly used as light sources for lighting devices, such as various lamps used indoors and outdoors, liquid crystal displays, electric signboards, and street lamps.